New tetranuclear macrocyclic complex: Crystal structure, magnetic property and DNA cleavage activity

Abstract A new tetranuclear complex[Cu 4 L 2 (bipy) 2 ](ClO 4 ) 2 ·H 2 O] has been obtained and fully characterized (where bipy = 4,4′-bipyridine, H 2 L is the macrocycle obtained from [2 + 2] condensation reaction between 2,6-diformyl-4-methylphenol and 1,3-diaminopropane). It exhibits a wheel-like configuration in which two bipy molecules connect two dinuclear [Cu 2 L] 2+ units. The magnetic measurement of the complex reveals that there is a strong antiferromagnetic coupling ( J  = − 383.88 cm − 1 ) between two Cu(II) ions in the macrocyclic unit and ferromagnetic interaction ( j ′ = 10.21) between the Cu(II) ions in two adjacent macrocyclic units. The interactions of the complex with calf thymus DNA were studied by UV–vis and CD spectroscopic techniques and the binding constant of between them is 1.74 × 10 4  M − 1 .